Steam superheater



June 12, 1928.

H CRUSE ET AL} STEAM SUPERHEATER Filed July 23, 1927 2 Sheets-Sheet 2 TI- 9 0 8 0 0 o 0 0 0o 0 o o o O o 0 o o ,M m y m u 0 O 0 0 O O O O O.

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UNITED STATES 1,673,231 PATENT, orFlcE.

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Application filed July 23, 1927, Serial Nd. 208,027, and. in Great Britain August 4, 1926.

This invention relates to steam superheaters and more particularly to superheater-s for use with fire tube type boilers, such as locomotive boilers, in which the superheat- -ingtubes project into the ends of the fire placed one within the other, the two tubes being secured together by welding or otherwise at both ends and the inner tube being shaped, except at one end, where it is cylindrical, to an elliptical or like form, dividingthe space within the outer tube into three portions, the inner elliptical space serving for the passage of the hot gases, and the two spaces on the opposite sides of the inner tube servingtor the flow and return of I, the steam being superheated, .the annular space around the cylindrical end of the in ner tube serving torthe transfer of the steam from the said flow to the said return space.

Referring to the two accompanying sheets of explanatory draw1ngs:

Figure 1 is an end elevation (with parts in section) and Figure 2 a sectional side elevation showing a part of the smoke box end of a locomotive boiler having our invention applied thereto.

Figure 3 is a similar view to Figure 1 showing a modified arrangement of the superheater elements.

Figure 4 is a plan showing the return end of one of the superheater elements.

Figures 5 and 6 are sections to a larger scale than that of the aforesaid figures, of two alternative forms of the superheaterelements.

The same reference letters in the different views indicate the same or similar parts.

In one convenient application of our invention. and as illustrated at Figures 1 and 2, each superheater element which is inserted within a fire tube a of the boiler, comprises two cylindrical tubes (7 and c disposed within one another and such as to provide a space between them. At one end (the return end) the inner tube 0 is retained of cylindrical shape and is secured to the outer tube 1) by space between the tubes. The said circular. I

portion ofthe tube 0 is shown at a, Figure t. The rema nder of the inner tube 0 is tormed to an ellipt cal or l ke section with the outside dimensions at its major axis equal to or slightly greater than the normal bore or internal diameter of the outer tube so that the space between the inner and outer tubes is dividedinto two partsserving for the flow and the return of the steam being superheated, as is shown by the sectional parts in Figure 1. The inner tube at its end where the steam enters and leaves the superheater element is of oval or like shape and is secured to the outer tube.

The inner oval or like tube a; may be formedso that its major axis externally may be slightly greater than the internal diameter of the external tube b, the latter being heated to cause it to expand, and permit it to be shrunk onto, or otherwise forced on toor over the internal oval or like tube 0. after which, bythe cooling of the outer tube 12 shrinkage will take place, giving permanent contact or connection, and resulting in the outer tube being formed slightly ellipticaL. .The pressure of the steam between the two tubesacting externally upon the oval or elliptical internal tube 0 will tend to expand the latter at its major axis. and acting internally upon. the external tube will tend to contract the latter at its major axis.

It will be seen that the whole of the space between the inner and outer tubes is divided I into two parts except at the end 0 (Figure 4:) where the inner tube 0 is cylindrical and where the steam being superheated is transferred from the flow to the return space of the superheater element. The space within the inner tube serves for the passage of the hot gases, as likewise does the space be tween the outer tube (2 and the smoke or fire tube a.

Two alternative forms of the tubes Z2 and c of the superheater elements are shown at Figures 5 and 6. In both forms the spaces for the hot gaseous products of combustion are indicated by d and the steam spaces by e.

The outer tube b'may have branches as f thereon to which steam inlet and outlet pipes may be secured. Or the branches ofthe outer tubes disposed vertically above and below (as with the example shown at Figures 1 and 2) or horizontally side by side of one another (as with the example shown way, or at the sides of its horizontal length from one'or'morevertical pipes.

By passing the hot gases both on the 1nside and the outside of the steam being superheated, we obtain a large heating surface,one portion of which 1s clear of the cooling effect of the adjacent water heating surface. 7

. What we (31211111 1s 1. In steam super-heaters, a superheatmg 'elementconsisting' in part of two tubes nested the one within the other, the outer tube being cylindrical throughout and the inner tube elliptical for the greater part of its length,'but having a cylindrical portion at one end forming an annular space between the tubes, the major axis of the elliptical portion being substantially equal to the internal diameter of the outer tube.

2. In steam superheaters, a superheating elementconsistin g in part of two tubes nested the one within the other, and permanently secured together at each end, the

outer tube being cylindrical throughout and the inner tube elliptical for the greater part a boiler fire tube of its length but having a cylindrical portion at one end forming an annular space between the tubes, the major axis of the elliptical portion being substantially equal to the internal diameter of the outer tube.

k 3. In steam super-heaters, the superheating element consisting in part of two tubes nested the one within the other, and permanently secured together at each end, the outer tube being cylindrical throughout and the inner tube elliptical for, the greater part of its length but having a cylindrical portion at one endforming an annular space between the tubes, the major axis of the elliptical portion being substantiallyequal to the internal diameter of'the outer tube, and the .two tubes major axis. 1

4:. In steam superheaters, a jsuperheating element consisting in part of two tubes nested the one within the other, the'outer tube being cylindrical throughout and the inner tube elliptical for the greater part of its length,'but having a cylindrical portion at one endforming an annular space between the tubes, the major axis of the elliptical portion being substantially equal to the internal diameter of the outer tube, steam inlet and outlet branches on the outer tube and in which said element is inserted. i In testimony whereof we have signed our names to this specification.

HENRY ORUSE. TOM FREDERICK GRAY.

permanently connected along'such 

